JPH05136208A - Semiconductor device and its manufacturing method - Google Patents

Abstract

PURPOSE:To enhance the quality of a semiconductor device manufactured in a mounting method wherein, after a semiconductor image sensor chip is arranged through ultraviolet-ray curing insulating resin at a specific location on a translucent circuit board on which a thick film conductive electrode is formed, the resin is irradiated with ultraviolet rays to secure the chip, and electrical conduction is effected. CONSTITUTION:A thick film conductive electrode 22 of a connection is so constructed that, after Au paste is applied by a screen printing method, leveled, dried and sintered, a polished surface on an upper part of this film is formed. Also, a polished surface 23 is formed on an upper part of the thick film Au electrode 22 film, whereby such a film can be realized that a cross-sectional shape is trapezoid and that the film thickness is uniform. The allowable range of misalignment in mounting is mounting is widened, and also the deformation amount of the thick film Au electrode or the load amount on a semiconductor chip can be reduced and a semiconductor device with high quality can be made in which fails of electrical connection or damages on a semiconductor image sensor chip 30 are reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to semiconductor mounting, and more particularly to a semiconductor device such as an image sensor for converting an optical image into an electric signal and a manufacturing apparatus thereof.

[0002]

2. Description of the Related Art In recent years, for the purpose of mounting a high-density multi-terminal, narrow-pitch semiconductor, an electrode of a circuit board having a conductor wiring is contacted with a bump electrode on a semiconductor element by a light or thermosetting insulating resin. Mounting method for fixing by fixing
No. 44742, for example. In addition, recently, since the bump electrodes of the semiconductor element are formed by plating with Au or the like, it is expensive, and therefore a mounting method without using bumps has been proposed.

An example of the conventional semiconductor device having no bump will be described below with reference to the drawings.

FIG. 4 is a perspective view of an image sensor manufactured by a conventional mounting method, and FIG. 5 is a sectional view of the main part thereof. Further, FIG. 6 shows a manufacturing process diagram of the translucent circuit board. Figure 4,
In FIG. 5, 1 is a glass substrate having translucency, 2 is a thick film Au electrode formed by a normal screen printing process, and 3 is a circuit conductor layer connected to this thick film Au electrode 2. The circuit conductor layer 3 includes a thick film lower Ag conductor 4 connected to the thick film Au electrode 2, a thick film insulating layer 5, a thick film upper Ag conductor 6 connected to an input / output terminal portion to an external circuit, and The thick film protective layer 7 is configured to protect the thick film upper Ag conductor 6. Reference numeral 8 denotes a semiconductor image sensor chip. The semiconductor image sensor chip 8 is an element 9 of an active element or a passive element formed by using a semiconductor process, an insulating layer 10, an Al wiring 11 and a protective layer 12 electrically connecting each element 9. , An Al electrode 13 formed on the surface of the protective layer 12 and connected to the Al wiring 11. Reference numeral 14 is an ultraviolet curable insulating resin for fixing the semiconductor image sensor chip 8 and establishing electrical conduction.

A method of manufacturing the image sensor having the above structure will be described below. First, by using a semiconductor process, the active element or passive element 9 or A
An Al electrode 13 is formed on the surface of the protective layer 12 of the semiconductor chip 8 on which the l wiring 11 is formed. Next, as shown in FIG. 6, the circuit board is previously coated with the Au paste by the screen printing method on the translucent glass substrate 1 and left at room temperature for leveling. Then, it is dried at 120 to 150 ° C. for about 10 minutes and then baked at a temperature of about 500 ° C. to form the Au thick film electrode 2. By repeating the same process, the thick film lower Ag conductor layer 4, the thick film insulating layer 5,
The thick film upper Ag conductor layer 6 and the thick film protective layer 7 are formed to form the circuit conductor layer 3. Finally, scribing is performed to prepare a translucent circuit board in an individual state. Then, a required amount of the translucent ultraviolet curable insulating resin 14 is applied onto the produced translucent circuit board, and the semiconductor image sensor chip 8 is contacted with the Al electrode 13 and the thick film Au electrode 2 thereon. Press against. At this time, the resin 1 on the thick film Au electrode 2
4 is pushed away, and the thick film Au electrode 2 and the Al electrode 13 are electrically connected. Thereafter, pressure is applied from the side opposite to the element 9 surface of the semiconductor image sensor chip 8, the thick film Au electrode 2 and the Al electrode 13 are pressure-bonded, and ultraviolet rays are radiated from the rear surface of the transparent circuit board to cure the ultraviolet curable resin 14. Cure. In this way, the semiconductor image sensor 8 is mounted on the translucent circuit board. At this time, the load applied to ensure a reliable electrical connection is such that the thick Au electrode 2 that abuts the spontaneously formed insulating oxide film of the Al electrode 13.
Just enough to physically destroy at. (For example, Japanese Patent Laid-Open No. 2-272764)

[0006]

However, in the above structure, the internal stress accumulated in the thick-film Au electrode 2 causes a disconnection of the electrical connection due to a change with time, and the back surface of the semiconductor image sensor chip 8 is exposed. However, there is a problem that the semiconductor image sensor chip 8 is damaged due to the excessive load.

The reason for this is that the thick film Au electrode 2 formed by the usual screen printing method has a variation in height as shown in FIG. 7A as compared with the Al electrode 13 on the semiconductor image sensor chip 8 side. 7B is so large that (B) of FIG.
When the electrodes are brought into contact with all of the electrodes as shown in FIG. 6, the other thick film Au electrodes 2-b are mainly deformed until the distance between the electrodes reaches the distance of the thick film Au electrode 2-a. This is necessary because the internal stress becomes extremely large depending on the amount of deformation of the Au electrode 2-b at this time, and the load from the back surface of the semiconductor image sensor chip 8 required for this deformation becomes excessive. Therefore, the occurrence of defects can be prevented by suppressing the variation in the film thickness between the thick film Au electrodes 2 and making the film uniform. In addition, since the cross-sectional shape of the thick film Au electrode 2 formed by the screen printing method is parabolic and has a large variation in the peak position, the position range in which all the electrodes can come into contact is narrow, resulting in poor electrical connection. It caused the occurrence.

In view of the above problems, the present invention provides a high-quality semiconductor device device manufactured by a flip-chip mounting method that reduces defects relating to a semiconductor chip and electrical connection and that simplifies the manufacturing method, and a manufacturing method thereof. It is a thing.

[0009]

In order to solve the above-mentioned problems, a semiconductor device of the present invention comprises a translucent circuit board having a circuit conductor layer and a thick film conductive electrode connected to the circuit conductor layer on the upper surface. , A semiconductor element is provided on the upper surface of the transparent circuit board through a photo-curable insulating resin, and pressure is applied from the side opposite to the element surface of the semiconductor element to apply thick film conductivity at a predetermined position of the transparent circuit board. In the semiconductor device in which the semiconductor element is fixed and electrically connected by irradiating ultraviolet rays to cure the photo-curable insulating resin with the conductive electrode and the electrode formed on the element surface of the semiconductor element in contact with each other, The membrane conductive electrode has a configuration in which a conductive paste is applied by a screen printing method, then leveling, drying, and firing are performed, and then the upper portion of the conductive film is polished to form a polished surface. is there.

[0010]

According to the present invention, the thickness of the thick-film conductive electrode can be made uniform by the above-mentioned constitution, and the contact of the electrode
The amount of deformation of the thick-film conductive electrode and the load on the semiconductor element during pressure bonding are small. Therefore, the accumulated internal stress is reduced and the load applied to the semiconductor image sensor chip is reduced. Further, since the thick-film conductive electrode has a trapezoidal cross-sectional shape, the allowable range for positional displacement at the time of contact / pressure bonding becomes large. For this reason, the occurrence of disconnection of the electrical connection due to a change with time due to the internal stress accumulated in the thick film conductive electrode, the defective electrical connection due to the position shift, and the excessive load on the back surface of the semiconductor element cause the semiconductor element It is possible to solve the conventional problem of damage of the.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor device and a method of manufacturing the same according to one embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of an image sensor according to an embodiment of the present invention, and FIG. 2 is a sectional view of a main part thereof.
Further, FIG. 3 shows a schematic view of a polishing apparatus used in the production. In the description, the same process as the conventional process will be described with reference to FIG. In FIG. 1, FIG. 2 and FIG.
Reference numeral 21 is a light-transmissive glass substrate, 22 is an Au electrode formed by applying an Au paste by ordinary screen printing, drying and firing, and 23 is this fired thick film Au.
Reference numeral 24 is a polished surface obtained by polishing the upper part of the electrode film, and 24 is a circuit conductor layer connected to the thick film Au electrode 22. The circuit conductor layer 24 includes a thick film lower Ag conductor 25 connected to the thick film Au electrode 22, a thick film insulating layer 26, and a thick film upper Ag conductor 27 connected to an input / output terminal portion to an external circuit. Thick film upper Ag
It is composed of a thick film protective layer 28 that protects the conductor 27. Reference numeral 29 is a strip-shaped reference region in which the Au electrode 22 and the circuit conductor layer 23 are not formed. Reference numeral 30 is a semiconductor image sensor chip, and 31 is an element such as an active element or a passive element formed by a semiconductor process. 32 is an insulating layer,
Reference numeral 33 is an Al wiring that electrically connects each element 31.
Reference numeral 34 is a protective layer, and 35 is an Al electrode formed on the surface of the protective layer 34 and connected to the Al wiring 33. Reference numeral 36 is a translucent ultraviolet curable insulating resin. Next, in FIG. 3, in the polishing apparatus, 37 is a frame having rigidity, and 38 is a frame.
Is a pair of upper rollers of the same shape attached to the frame 37 at a position where only the strip-shaped region 29 is in contact and running, 39 is a rotary grinder for polishing the Au electrode 22 installed on the frame 37, and 40 is the glass substrate 21. It is a loader roller for carrying. Reference numeral 41 is a spring that connects the frame 37 and the loader roller 39.

A method of manufacturing the image sensor having the above structure will be described. First, a light receiving element such as a phototransistor or a photodiode is formed on a single crystal silicon substrate (wafer) using a semiconductor process,
A device provided with an element 31 such as an access circuit such as a CCD, a MOS, or a bipolar IC is manufactured. Al wiring 33,
A two-layer Al wiring process is used for the protective layer 34 and the Al electrode 35, and the Al electrode 35 is formed to have a film thickness of about 1 μm by a sputtering method. Thereafter, this wafer is cut by a high precision dicing technique to manufacture the semiconductor image sensor chip 30. In addition, a circuit board is prepared in advance.
By the screen printing method as before, first, Au
The paste is applied on the main surface of the glass substrate 21 and left at room temperature for leveling. Then 120-1
After drying at 50 ° C. for about 10 minutes and firing at a temperature of about 500 ° C. to form the Au thick film electrode 22, the thick film lower Ag conductor 25, the thick film insulating layer 26, and the thick film upper part are sequentially formed in the same manner. The Ag conductor 27 and the thick film protective layer 28 are formed to form the circuit conductor layer 24. However, at this time, two or more strip-shaped reference regions 29 where the Au electrode 22 and the circuit conductor layer 23 are not formed are provided on the glass substrate 21. Finally, scribe to individual state. After that, the upper part of the Au thick film electrode 22 is polished by rotating the rotary grinder 39 by the polishing apparatus shown in FIG. 3 to form the polishing surface 23, and the film thickness is made uniform and the cross-sectional shape is trapezoidal. Do things. In this polishing apparatus, a pair of upper rollers 38, which are in contact with the strip-shaped reference area 29 on the glass substrate 21 and are running, make the reference area 29
Since it moves up and down following the irregularities of the rotary grinder 3 installed on the upper roller 39 through the frame 36.
9 moves up and down in conjunction with each other, and the distance between the rotary grinder 39 and the upper surface of the glass substrate 21 is always constant. In addition, the pressure when the upper roller 38 contacts the upper surface of the glass substrate 21 by the spring 41 through the loader roller that conveys the glass substrate 21 by rotating while contacting with the back surface of the glass substrate 21 becomes appropriate and constant. It has become. Therefore, highly accurate uniformization of the film thickness can be realized. Further, the rotary grinder 39 has a mechanism which can be vertically and horizontally variable with respect to the frame 37, so that the rotary grinder 39 can be finely adjusted when it is worn out, thereby ensuring the durability and reliability of the apparatus. it can. Next, similar to the conventional example, an acrylate-based translucent UV-curable insulating resin 36 is applied to a predetermined position on the translucent circuit board by a simple mounting method by a predetermined amount by a stamping method or a screen printing method. To do.
On top of that, the semiconductor image sensor chip 30 and the Al electrode 3
5 and the polishing surface 23 of the thick film Au electrode 22 are pressed against each other. After that, pressure is applied from the side opposite to the surface of the element 31 of the semiconductor image sensor chip 30, and the thick film Au electrode 22
The Al electrode 35 is pressure-bonded, and ultraviolet rays are irradiated from the back surface of the glass substrate 21 to cure the ultraviolet curable resin 36. At this time, since the film thickness of the thick film Au electrode 22 is very uniform, the deformation amount of the thick film Au electrode 22 becomes small, and the load on the semiconductor image sensor chip 30 becomes sufficiently small. In addition, since the cross-sectional shape is trapezoidal, the allowable range for the positional displacement at the time of contact is large, and the defective electrical connection due to the positional displacement is reduced. In this way, the semiconductor image sensor chip 30 is mounted on the translucent circuit board.

The image sensor is manufactured as described above. For this image sensor, the glass substrate 21
Also, the light receiving element in the element 31 formed on the semiconductor image sensor chip 30 detects the optical information through the transparent ultraviolet curable resin 36 and converts it into an electric signal.

As described above, according to this embodiment, in the semiconductor device which can be manufactured by a simple mounting method,
After the thick film Au electrode is formed on the translucent circuit board by the usual screen printing method, the thick film Au electrode film is polished on its upper surface to form a polished surface, so that the cross-sectional shape is trapezoidal. The film has a uniform thickness, and for the above reasons,
It is possible to provide a high-quality semiconductor device with few defects in semiconductor elements and electrical connections.

[0016]

As described above, in the semiconductor device of the present invention, the transparent circuit board having the circuit conductor layer and the thick film conductive electrode connected to the circuit conductor layer on the upper surface, and the upper surface of the transparent circuit board. A semiconductor element is arranged at a predetermined position through a photo-curable insulating resin, and pressure is applied from the opposite side of the element surface of the semiconductor element,
In the semiconductor device in which the semiconductor element for fixing and electrically connecting the semiconductor element by irradiating ultraviolet rays to cure the photo-curable insulating resin in a state where the electrode formed on the element surface of the semiconductor element is in contact with the thick film, The conductive electrode is applied with a conductive paste by a screen printing method, then leveled, dried and baked, and then the upper surface of the film is polished to form a polished surface, so that the cross-sectional shape becomes trapezoidal. In addition, since the film thickness can be made uniform with high accuracy, it is possible to obtain a high-quality semiconductor device in which damage to the semiconductor chip and defective electrical connection are reduced by a simple construction method.

[Brief description of drawings]

FIG. 1 is a perspective view of a semiconductor device according to an embodiment of the invention.

FIG. 2 is a cross-sectional view of essential parts of a semiconductor device in the example.

FIG. 3 is a schematic view of a polishing apparatus in the same embodiment.

FIG. 4 is a perspective view of a conventional semiconductor device.

FIG. 5 is a sectional view of a main part of a conventional semiconductor device.

FIG. 6 is a manufacturing process diagram of a circuit board of a conventional semiconductor device.

FIG. 7 is an explanatory diagram of causes of defects in a conventional semiconductor device.

[Explanation of symbols]

 1, 21 Light-transmissive glass substrate 2, 22 Thick film Au electrode 3, 24 Circuit conductor layer 4, 25 Thick film lower Ag conductor 5, 26 Thick film insulating layer 6, 27 Thick film upper Ag conductor 7, 28 thickness Film protective layer 8,30 Semiconductor image sensor chip 9,31 Element 10,32 Insulating layer 11,33 Al wiring 12,34 Protective layer 13,35 Al electrode 14,36 UV curable insulating resin 23 Polished surface of thick film Au electrode 29 Belt-shaped Reference Area 37 Frame of Polishing Device 38 Pair of Upper Rollers 39 Rotating Grinder 40 Loader Roller for Transferring Substrate 41 Spring

Claims (4)

[Claims] 1. A translucent circuit board having a circuit conductor layer on its upper surface and a thick film conductive electrode connected to the circuit conductor layer, and a semiconductor on the upper surface of the translucent circuit board via a photocurable insulating resin. The device has an element, and pressure is applied from the side opposite to the element surface of the semiconductor element, and the thick film conductive electrode and the electrode formed on the element surface of the semiconductor element are brought into contact with each other at a predetermined position of the translucent circuit board. In the semiconductor device in which the semiconductor elements are fixed by electrically irradiating the photo-curable insulating resin by irradiating the ultraviolet rays in the above state, and the thick film conductive electrodes are conductive paste by a screen printing method. After applying, leveling, drying, and baking, and then polishing the upper surface of the thick conductive film to form a polished surface. 2. The semiconductor device according to claim 1, wherein the thick film conductive electrode is Au. 3. The semiconductor device according to claim 1, wherein the semiconductor element is an image sensor. 4. The polishing of the film upper portion of the thick film conductive electrode is carried out at two independent locations on the upper surface of the transparent circuit board, where the strip-shaped thick film conductive electrode and the reference region where the circuit conductor layer is not formed are independently formed. A thick film on the upper surface of the translucent circuit board via a pair of rollers of the same shape arranged so as to contact only the strip-shaped reference region and to travel, and a frame having rigidity with the rollers. In a structure in which a rotating grinder installed at a predetermined position on a conductive electrode and a rotating roller are arranged in the frame so as to come into contact with the lower surface of the transparent circuit board via a spring, the rotating roller is the transparent member. The transparent circuit board is conveyed by rotating the flexible circuit board while pressing it against the pair of rollers with an appropriate constant force by a spring force,
The rotating grinder detects irregularities in a reference area.
The polishing surface was formed by a polishing device equipped with a mechanism for rotating and polishing the thick film conductive electrode while keeping a constant distance from the upper surface of the transparent circuit board by interlocking with a pair of rollers. The method for manufacturing a semiconductor device according to claim 1, wherein